The NH-L9i is a low-profile quiet cooler designed for use in small form factor cases and HTPC environments. While it provides first rate performance in its class, it is not suitable for overclocking and should be used with care on CPUs with more than 65W TDP (Thermal Design Power). Please see the following table for our detailed recommendations and also read the explanations below:

Recommended with good case ventilation, Intel Turbo Mode disabled and typical
workloads only (not recommended for continuous 100% load on all CPU cores).

CPU temperatures depend on various different factors, so please take note of the explanations below and keep in mind that our recommendations can only serve as general guidelines for typical setups.

1) Our recommendations are based on an ambient temperature of 25°C or less. If your ambient temperature is significantly higher (30°C or more), we don’t recommend running the NH-L9i on 84W Haswell, 77W Ivy Bridge or 95W Sandy Bridge CPUs. For all other setups, please ensure good case ventilation when ambient temperature is 30°C or more.

2) Our recommendations assume that the cooler is installed in a typically equipped, properly ventilated HTPC system. If you are using particularly hot components inside your system, it may be necessary to use stronger case ventilation to ensure sufficient CPU cooling performance.

3) Our recommendations assume that the fan is used with PWM control (configured so that it can speed up to 100% when necessary) but without the supplied Low-Noise Adaptor. If you would like to use the NH-L9 with the supplied Low-Noise Adaptors, we recommend choosing CPUs with less than 65W TDP.

03.03.2015 - PureOverclock.comNF-A4x10 5V
Test verdict: "Overall, I believe Noctua makes an excellent product. There really isn’t anything I can complain about except for the price, and even then the price is understandable. If you need good air flow, low noise and have a small form factor case that needs some better fans, I could definitely recommend what Noctua has to offer here." (Josh Jackson, PureOverclock.com)

03.03.2015 - FrostyTech.comNH-U9S
Test verdict: "Given these height and footprint size restrictions, the Noctua NH-U9S is a pretty quiet heatsink that offers very good thermal performance in the sub-125mm tall heatsink category, making it an excellent choice for PCs which are severely space limited. The results are enhanced by adding a second fan, as we've shown over the course of this review. Couple that with awesome build quality and a 6 year warranty and it's not hard to recommend this cooler." (Max Page, FrostyTech.com)